Two high-profile reports in Newsweek magazine on Israel’s espionage campaign against its American allies are a sign that the relationship between the two countries has sunk to a new low point.

The reports quote former American intelligence officials and Congressional staffers who claim that Israel has “crossed red lines” in its attempts to obtain confidential information.

The Newsweek reports mainly contain quotes from unnamed American sources and, besides an unattributed story of a man hiding in the air vents of former vice president Al Gore’s hotel room during a visit to Jerusalem 16 years ago, offer no new details.

The claims that Israel conducts more aggressive spying against America than any of its other allies run counter to assurances of senior Israeli intelligence chiefs. They say that since the sentencing of Jewish-American spy Jonathan Pollard in 1987, Israel has been extremely careful not to conduct spying missions on US soil. Israeli ministers denied the claims, with Strategic Affairs Minister Yuval Steinitz insisting that “Israel does not spy in the US, does not enlist spies in the US, and does not do intelligence gathering in the US.”

Foreign Minister Avigdor Liberman also claimed that he “would not agree to any spying on the United States”.

Israeli officials are concerned that the reports, which have been linked to the opposition in the American administration to Israel joining the visa-waiver programme, were timed to dampen any official Israeli criticism of a possible deal between the P5+1 group of powers and Iran over its nuclear project.

The Obama administration’s eagerness to reach an agreement with the Iranians has increased as other foreign policy initiatives — such as the peace process and the establishment of a new trade agreement with countries in Asia — have foundered. While the strategic alliance between the two countries remains strong, there is a great deal of distrust. The Iranian talks are a further source of friction.